The present invention relates to a new and improved construction of apparatus for exchanging pouring tubes at a casting vessel of the type having a closeable bottom pour discharge nozzle or opening during the continuous casting of metals, especially steel, wherein a vertical pouring tube which protrudes into an open-ended vessel is equipped with guide means which provide for such pouring tube a path of movement out of an approximately horizontal infeed or introduction position into a substantially vertical casting position.
During the continuous casting of metals tubular-shaped protective devices are used both between the casting ladle and the tundish as well as also between the tundish and the continuous casting mold in order to protect the casting or teeming jet against oxidation. Such tubular-shaped protective devices enclose the teeming jet either over its entire length or over a part of its length and will be referred to hereinafter as pouring tubes. Such pouring tubes which are fabricated of refractory material are exposed to wear, especially when used for pours lasting over longer periods of time. Therefore, especially in the case of continuous casting installations for steel strands there exists the need to structure such pouring tubes so as to be exchangeable during the casting operation. The removal of such pouring tubes out of their casting position and the re-introduction of the same or other pouring tubes back into the casting position can also be desired, for instance, for carrying out flame work, typically for instance flame-descaling or flame-chipping operations, by means of an oxygen lance at the bottom pour opening or discharge nozzle of the casting vessel.
An apparatus for exchanging pouring tubes at a casting vessel in the form of a tundish of a continuous casting installation has become known to the art, wherein a pouring tube which extends below the level of the metal bath of an open-ended vessel in the form of a continuous casting mold cooperates with a closeable bottom pour opening. This pouring tube can be pivoted along a path between an infeed station and the casting station. During such pivoting the lengthwise axis of the pouring tube remains in its horizontal infeed position. By carrying out a further pivoting movement about a pivot axle connected with the guide the pouring tube can be brought at the casting station above the mold out of its horizontal position into a vertical casting position and thereafter is concentrically attached to the bottom pour opening of the tundish. The contemplated pivoting about the pivot axle or shaft requires a certain amount of free space within the mold in accordance with the pivot arc or circle of the outfeed end of the pouring tube. With slab widths of 1.2 meters and more sufficient space is available, as a general rule, within the mold for carrying out the aforementioned pivotal movement. In the case of smaller slab-, bloom- or billet- cross-sections the infeed or introduction cross-section or area for receiving the pouring tube is small and, therefore, such pouring tube must be rocked into the vertical position above the mold and thereafter immersed into the hollow mold compartment and the molten metal bath contained therein. The raising and lowering of the pouring tube is especially disadvantageous when working with tundishes equipped with a number of bottom pour outlets or discharge nozzles, as such are used in multi-strand casting installations. When raising the tundish for the purpose of exchanging a pouring tube the continuous casting operation is disturbed at all of the strands supplied with steel from the tundish. This disturbance is especially disadvantageous for metallurgical reasons when casting with flux powder.
Further, there is known to the art an apparatus which uses a pouring tube for protecting a casting or teeming jet between a casting vessel in the form of a ladle and a throughflow vessel in the form of a tundish. This pouring tube is elevationally adjustable by means of a lever mechanism mounted at the tundish, in order to thereby provide a tight or sealed connection with the ladle. This prior art equipment is not designed for the removal of a pouring tube from the tundish and for exchanging pouring tubes.